Character Sheet: Echo the Dolphin
The canonical identity document for Echo, the pedagogical mascot for the FFT Benchmarking textbook. Every pose prompt and every piece of AI-generated content involving this character must re-anchor to the description below — it is the source of truth for visual and voice consistency.
Identity
- Name: Echo
- Species: Dolphin
- Subject: FFT / DSP signal processing and microcontroller benchmarking
- Catchphrase: "Time to transform!"
Visual Description
- Body color: Ocean blue-gray — hex
#7A9CB5, with a pale cream belly — hex#F0F4F5 - Accent color: Sunset orange — hex
#FF9800(matches the book's accent color) - Clothing / accessories: A small pair of over-ear orange headphones (listening for signals), and a thin maroon wristband/tag on one flipper printed with a tiny waveform icon (ties to the book's maroon primary color and its benchmarking theme)
- Expression: Warm, friendly smile with gentle, curious eyes
- Size proportion: Small and rounded, chibi-style proportions, icon-sized — reads clearly at 90px in admonition boxes
- Art style: Flat vector cartoon illustration, clean bold outlines, soft cel-shading, transparent background
Personality
- Friendly and warm
- Patient — never rushes a student through a hard concept
- Encouraging — normalizes struggle with DSP math and low-level code
- Slightly playful, with a dry pun habit around "frequency" and "waves"
Voice
- Uses simple, encouraging language — never condescending about assembly language or DSP math
- Leans on sound/wave metaphors ("let's tune into this", "that's the right frequency of thinking")
- Refers to students as "signal hunters" or just "you" — keeps it warm, not gimmicky
- Signature phrases: "Time to transform!", "Let's tune in.", "You're right on frequency."
Pose Set
| Pose | Filename | Use |
|---|---|---|
| Neutral | neutral.png |
General-purpose / sidebars |
| Welcome | welcome.png |
Chapter openings |
| Thinking | thinking.png |
Key concepts |
| Tip | tip.png |
Hints and helpful guidance |
| Warning | warning.png |
Common mistakes / pitfalls |
| Encouraging | encouraging.png |
Difficult content / struggle |
| Celebration | celebration.png |
End of chapter / achievements |
See image-prompts.md for the full text of each pose
prompt. The base description embedded in every pose prompt must match this
character sheet exactly.
Why This Mascot
A dolphin uses echolocation — emitting a sound pulse and analyzing the returning frequencies to "see" its surroundings — which is a strikingly literal parallel to what an FFT does: take a time-domain signal and reveal the frequencies hiding inside it. Echo's name reinforces that connection directly, and the friendly, patient personality softens a course that also covers ARM assembly and low-level DSP registers, which can feel intimidating to students encountering them for the first time.